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Date:   Mon, 21 Jan 2019 16:34:40 +0100
From:   Thierry Reding <treding@nvidia.com>
To:     Robin Murphy <robin.murphy@arm.com>
CC:     <iommu@lists.linux-foundation.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <m.szyprowski@samsung.com>,
        <hch@lst.de>, <rmk+kernel@armlinux.org.uk>, <bskeggs@redhat.com>,
        <tjakobi@math.uni-bielefeld.de>, <b.zolnierkie@samsung.com>
Subject: Re: [PATCH] ARM: dma-mapping: Clear DMA ops on teardown
Message-ID: <20190121153439.GA21078@ulmo>
References: <2f5833b7639543d614095cd3f5ab0dc0274e26d6.1548081277.git.robin.murphy@arm.com>
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On Mon, Jan 21, 2019 at 02:52:16PM +0000, Robin Murphy wrote:
> Installing the appropriate non-IOMMU DMA ops in arm_iommu_detch_device()
> serves the case where IOMMU-aware drivers choose to control their own
> mapping but still make DMA API calls, however it also affects the case
> when the arch code itself tears down the mapping upon driver unbinding,
> where the ops now get left in place and can inhibit arch_setup_dma_ops()
> on subsequent re-probe attempts.
>=20
> Fix the latter case by making sure that arch_teardown_dma_ops() cleans
> up whenever the ops were automatically installed by its counterpart.
>=20
> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in arm_iommu_de=
tach_device()"
> Tested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>=20
> Sorry for the delay - there was a giant email infrastructure cock-up just
> at the point I wanted to go back through my archive and double-check the
> discussion around the original commit...
>=20
> Robin.
>=20
>  arch/arm/mm/dma-mapping.c | 2 ++
>  1 file changed, 2 insertions(+)

I had also tested your draft on Tegra last week and this looks
identical, so:

Tested-by: Thierry Reding <treding@nvidia.com>

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